Re: [Haskell-cafe] instance Alternative (Either [a])

On Thu, May 22, 2014 at 05:10:24PM +1000, Tony Morris wrote:

AccValidation has an Applicative instance that accumulates on "Left" (Failure) as per the previous email. Therefore, it has no Monad.

This applicative is called Errors in the transformers package (in Control.Applicative.Lift, of which it's a special case).